Since the Disney and Fox merger happened on top of production delays and reshoots, Josh Boone's The New Mutants now sits on quite a weird place. Despite being a part of the franchise, The New Mutants isn't connected with the main X-Men but the movie's new synopsis might give a better idea of where it's exactly set.
20th Century's official website provides a lengthy breakdown of what to expect in the movie. However, the "odd" name out in the synopsis is Colossus, a character featured in the 2 Deadpool movies and 4 main X-Men movies. He was mentioned as Magik's brother, but of course, this isn't news because the familial link has been present in the comics. You can check out the portion of the namedrop below:
The younger sister of Colossus, Magik becomes encased in armor at will and wields a soulsword that amplifies her multiple superhuman and psychic abilities. Invited by Dr. Cecilia Reyes (Alice Braga) to share their stories about when their powers first manifested, the five "patients" come to understand that they are in a class of people called mutants, who have historically been marginalized and feared. As they relive their origin stories, their memories seem to turn into terrifying realities.
This essentially points out that the movie is linked to the wider X-Men universe. That being said, Boone made it clear that the studio wanted to distance itself from the previous X-Men films as much as possible.
For now, it's unclear whether Colossus would make an appearance in the film and whether or not this namedrop is key for the Fox X-Men continuity before the heroes make their way to the Marvel Cinematic Universe.
The New Mutants is currently set for release on August 28.